Polymerizable composition of styrene, unsaturated alkyd resin, and elastomer



Patented Sept. 2, 1 952 PQLYMERIZABLE; comrosirloiy OE smiapNE, UNSA'LUItATEn ALKYD RESIN, AND

ELASTOMER Louis C. Rubens and Raymond Fa'B'oyer; Midland;- Mich-., assi'gnors to The Dow Chemioal-fionh many, acorporationofiiDelaware No' Drawing. Application. July lflf, 1,946.;- Serial. NO. 6824593 e Claims;

This-invention relates matic resins and resin-forming compositions.-

Ijhe interpolymerization of styrene with rough 1y equal or largerproportions oi an-unsaturated alkyd resinproduces plastic materials which a-re 5 used --com'rnercially as laminating and" casting resins, However; the-monomeric compositions are comparatively expensive; and thepolymericproducts have dielectric characteristics which limit-- their usefulness as insulating materials" where radio-frequency currents are involved;

It--is accordinglyanobj-ectof the inventionto provide improved vinyl aromatic lamina-tingandcasting compositions which are materially less expensivethan those heretofore-- used for these purposes and-which -polymerize rapidly to-resins havingexcellentphysical and electricabproper tiesw.. l .r l

V Theinvention is based on thediscoverythat a small-proportion ot-an unsaturated I alkyd-resin- 2o markedly accelerates-the rate-of polymerization of-;sty-rene and other monovinyl a-romatie-eompounds, and that the resultingpolymers possessvery desirable physical properties whilelargely retaining-the excellent dielectric charaeter-istics of-the pureviny-l" aromatic polymers, Bwta-ki-ng advantage of this discovery; a number- 013* 'exceptional larriinating arrd casting resin -compo sitionsma-y be formulated; r 1 e In so far as known, the catalytic effect oi nn saturatedalkyd resinsis observed" inthepolymerizati'on ofpolymerizable monoviny u are matic compounds-generally; 'Typical of such materials are the monovinyi aromatic hydrocarbons and I halohydrocarbonssuch asstyrene, p-ethyl styrene, dimeth-yl styrene, p-ch lorosty rene, dichlorostyrene; and vinyl naphthalene=.-- Styrene is at present of principal commercialimportance; I

The term unsaturatedalkyd resini iollowing conventional practice; is here use'dtoarefer: to l the: unmodified and modified polyhydrie alcohol polyesters-oi I alpha -unsaturatedallpha-beta-pol ycarb'oxyli'c: acids.- Typical of the opolyhydri'e alcohols-used in making: such resins; are. ethylene. w glycol, din, tri-, and tetraeethylene glycol,-.pro= pylenei'glycol; dipropylene, glycol, trimethyl'cne glycol, glycerol, and pentaerythritol. Examples. of u the alphaunsaturated alpha beta-polycarboxyl ic acids-are male-i0, fumaric; chlorom aleic; so, chlorofiumaricg: citraconictandmesacon-ic acids: In" making theunmodified unsaturated alkyd resins, one: or more of 'thesforegoing' alcohols is heated -with a roughly equivalent proportion oi one or' more: of the acids named; their anhydridcs- 55,-

:to improved ;viny-l* arocompounds to-the extent of'w per cent, it isweil-k Zed-45:4);

or eempounds whichliberate theacids; foratime sufficient to complete condensation to aresinous: polyester. Inna-airing; modified unsaturated alkyd resins; apart; or even nearlyall; of the unsatur-' ated polycarboxylieacidmay be replaced by -asaturatedpolyor mono-carboxyl-ic acid; such-'- as succinic, adip-ic, phtha-lic, sebacic; or 12- hydroxy stearic acid. Such resins, both un modified andmodified; are available commerci-ally under-a varietyoi trade-names;

It will be noted that the molecule of eaclr' unsaturated alkyd resin: containsthe functional grouping (E. Q f t t'= 'm repeateclalongthe pol-yesterchain: The-presence of thisg-roup' is thought to account for the cata-- lytic activity of the unsaturated alkyd resin, since it has been observed that the more frequent the occurrence of the group-in-the-resin; the-greater I the catalytic effect, i.. e. the unmodified unsatu ratedzi alkyd resins are more active than the modified resins. It is essential" that theacti ve; groupbe repeated along the chain, i. e. that the; polyester: consist" of a number of aleohol -and acidunits. The simpleesters, obtained-by condensation of-- a single pol yhydric alcohoFmoleculeiwitha single polycarboxyli'c acid molecule, shown-no catalytic effect vWith the-polyesters; the activityiincreases as the molecular weightof the polyester increases. general; those un saturated alkyd resins having a molecularrwei ghti asl-measuredi by the acid value of the-resin; over-- r-are= quite effective, With molecular-weights;

over 1000 beingpreferred, A

The; proportion of unsaturated-alkyd re---. quired to. catalyze the polymerization (if-v ylF- aromat ic.compounds is not large, as=-Iow-as='-0.5 per cent: by weight of the totalpolymerizable materiali'being effective. Increasing proportions of theflr'esin givea somewhat greater-effect: In;- general, not over-l0- per cent of resin should be" used, since larger amounts impair-the dielectric properties ofthe polymer}; lto- 5 "per cent is preferred. With those unsaturated alky'ci resins. which are not soluble vinyl; aromatic toslimit the amount-of resinto that which wi 17 dissolve readily. Modified resins are somewhah 1 moresohtblfethan theunmodi fied ones. Small proportionsofunsaturated alkyd" resins; are not. onlyactive per sein eatal'yzing the poly" meri'zation of vinyl aromatic compounds butther are also elrective -in accelerating the rate of poly- 3 merization of such materials in the presence of conventional polymerization catalysts. By far the best results are obtained when the unsaturated alkyd resins are used to accelerate the polymerization of vinyl aromatic compounds in the presenceof organic peroxide catalysts, such as benzoyl and lauroyl peroxides. By using both an unsaturated alkyd resin and a peroxide, extremely rapid but controllable rates of polymerization may be realized and polymers of desirably high molecular weight prepared.

The unsaturated alkyd resin catalyst is not only effective in catalyzing the polymerization of monovinyl aromatic compounds alone, but is also active in the copolymerization of such compounds with lesser proportions of other polymerizable substances, i. e. in polymerizing monomeric materials generally in which a polymerizable monovinyl aromatic compound is the major polymerizable constituent.

In practice, the monovinyl aromatic compound to be polymerized, e. g. styrene, is mixed with 0.5 to 10 per cent by weight of an unsaturated alkyd resin, and another catalyst, if desired, e. g. 0.1 to

5 per cent of lauroyl peroxide, is added. The mixture is then heated at a polymerizing temperaturae. g. 50 C. or higher, until polymerization is complete. I

If it is desired to store the vinyl aromatic compound-unsaturated alkyd resin mixture at room temperature before use, a small proportion of a conventional inhibitor, e. g. p-tert.-butyl catechol or hydroquinone, may be added. Such inhibitor does not destroy the catalytic efiect of the unsaturated alkyd resin when polymerization is later initiated by heating.

l 3y utilizing the principles of the invention, a number of'laminating and casting resin compositions or extremely valuable properties. may be formulated.

Resin-forming compositions used in making laminates-with glass, cloth, paper, asbestos, or other fillers must meet a number of specifications. They should be readily applicable to the reinforcing material by dipdmpregnation, brushcoating, or flowing onto the material. They must set rapidly to form tough, insoluble, heat-resistant resins, They should also have a low cost.

1 Such compositions may be made, according to the invention, by incorporating into a mixture of a monovinyl aromatic compound, and an unsatu rated alkyd resin catalyst, a minor proportion of an elastomer. The addition of the elastomer,

which should be present in a proportion of about, 2 toaboutl5 per cent of the vinyl aromatic compound, serves to control the viscosity. of the.

monomeric solution and also to impart great toughness and high impact strength to the poly-v merized product. In so far as known, any uncured elastomer may be used, although hydrocarbon elastomers, such as butyl rubber and natural rubber are preferred. The 70 per cent butadiene-30 per cent styrene emulsion copolymer, known as GR-S, is especially effective.

lI'he usefulness of such laminating, compositions may be improved by also adding a small proportion ofa polymerizable polyolefinic compound, such as divinyl benzene, which, presumably by initiating cross-linking of the polymer chain molecules, causes the resin-forming mixture to gel during the initial stages of the polymerization. Suchgelation serves to thicken the mixture rapidly on heating, preventing loss'by flow from the material being laminated. Other cross-linking polyolefinic compounds include diallyl phthalate,

stated.

allyl acrylate, diallyl ether, glycol diacrylate, and many others. Such agents also act to raise markedly the heat-distortion temperature of the resulting polymer. In general, at least 1 per cent by weight of the polyolefiniccompound, and preferably 2 to '7 per cent, should be used. Values above 16 per cent should in general be avoided, since with such concentrations the polymeric product tends to be brittle. v

In'actual practice, the laminating compositions are made up by mixing the monovinyl aromatic compound, unsaturated alkyd resin, elastomer, and polyolefinic compound in the proportions Such a composition, preferably with an inhibitor added, may be stored until ready for use. At that time, an organic peroxide catalyst is preferably added and the liquid mixture applied to the reinforcing material to be laminated. The treated material is then cured under heat and pressure in conventional manner. The dielectric properties and impact strengths of the cured resins far excel those of laminating resins heretofore available.

As already suggested, the present invention also exceptional dielectric properties, and high re sistance to mechanicalshock, and must not flow at temperatures up to C., and yet must not be brittle in extreme cold. I

Casting compositions of this charatcer prepared, according-to the invention, by adding to a mixture of a-monovinyl aromatic compound and an unsaturated alkyd resin catalyst from 10 to 50 per cent by weight of an aliphatic-chain hydrocarbon polymer incompatible with the polymerized vinyl aromatic compound. butylene, polybutadiene, polyethylene, and the 70 per cent butadiene-30 per cent styrene emulsion copolymers known as GR-S and. as soluble Buna S, are typical incompatible aliphatic-chain hydrocarbon polymers, with polyisobutylene being preferred. On polymerization, such mixtures set to soft wax-like solids of excellent electrical characteristics which do not become brittle even at40C. g

vAS in the case of laminating resin formulations, it is desirable to incorporate in these vinyl aromatic compound-alkyd resin-hydrocarbon polymer casting mixtures from about 1 to about 10 per-cent, preferably 2 to 7 per cent, of a polymerizable polyolefiniccompound, suchas divinyl benzene; to insure'early gelation of; the'mono meric mixture on heating and to-raise the heats distortion temperature of the final product.- a

It is also desirable, in making this type of casting composition-for electrical use, to include-an inert filler tolimit shrinkage on polymerization. Preferred fillers should have a very low dielectric loss, such as chlorinated diphenyl resins, hydrogenated polystyrene, or hydrogenated polyindene;

The filler should ordinarily represent from 10 to 50 per cent by weight of the vinyl aromatic compound. I

In practice, the casting compositionsare formulated by mixing the monovinyl aromatic compound, unsaturated alkyd resin, aliphatic-chain hydrocarbon polymer, polyolefinic compound, and

filler in the proportions stated. Such a mixture, preferably with inhibitor added, may be stored untilready for useuAtthat time, an organic maybe Polyisoaeeaaea ,gnaes Wil emanate re notto be construed as limiting Example 1 stearilaci me t ain d. the pne n zof v. we he a b l twie ht Qt tba eliinsf esin was, @150 0 e i iiiatest rom ox-thmeteriali lei at? blank; @FQEFEIZQQQQQL sur mqeonier t; a 0 3119;" airs,

Styrene; hen healer. .7 4. polymerized-at the rate of-about 0;? percent per hour. A mixture of styrene with 1.0 per cent by weight of the unsaturatedalkyd resin prepared abs nce, 0; ver: t r e lxst he; small w portion. of? nsaturated: alkyd resin. more. than.

dqu e ithe atal i;a rmerizatioa.un eri ll.can

di iiibeatssted- Esamela In; a series of determinations, iniz-ztures.= of

styrene with a number of proportidnsof the unsaturated alkyd resin of Example 1 were polymerized at various temperatures, all with 0.2

t nie? enze lner d aa ata y t-, Th

b ae; eteaefii lrmerizat ea re charr d- Temper- We; Percent Alkyd Resin zation I lam-555GB Percent-.-

From eseitestst i s; $8361. 2 thatumthe p ence ofa. peroxide catalyst, asmall proportion-.-

on ns t rated alk drresininmdnce a eyerah ix-Fac t m?! An unmodified alkyd resin; waseprepared by heating together equi'moleciilarfproportions of triethylene glycol and inalei'c acid. Samples werewithdraw-n-at -i-ntervals--as the condensation proceeded, and the average molecular weight of the resin present in each sample was determined by measuring the acidnumber. In this way, the

the as. numb r From theseruns it will be noted'flthatimthe cwoap'olcppoc 3 liee e ei al of'the sal vaqieel m zatipe t aime Melee-111M i leis miili ale,

1 solidified Without gelation after 4$l1ours rem t s esul s. i s apparent. teatime,

'- simple ester possesses no catalytic efiect, that p lyesters ha ng. a. molecular weight; of: 5,001 or:- more; show activity,- and that the activitsg' in: creases with increasing molecular weight, 0ft the:

alkyd resin;

h mans laminating resinqcompositioniwae; prepared from; styrene; a2 diethylene: g ycolfefmnaric; a id n aturated; alkyd: resini havin a: moleoulan weight of about 8900, asolubleaBunmSsltubberr (R01 per cent butadieneeaflz perscentzstyrenezemulsl'om, copolymer),., and, a crude divinylnheilzen ncgnee taining about 40 per cent by: weightioffg haflm 4 terialhthe balance being ethyl styren'e;' These i ered sfweres mixed the-renewing; prunes tions: a

Ingredient {Fags-by Keisha Immediately prior to use, 1 per cent of'"lauroyl* peroxide was added to -the-lmix-ture as a catalyst. h mix uree ad h nons st n noial hinisyrup and could easily be spreadmn glass clothglog, therV s nforeina.mater alsbx ina nepr br sh: ing,

Test'gsheets'of the polymerized resin were made b z-heating"- the-syrupbetweenremovablaplatesa for-16 hoursatflil", C. .followedby zhours. at 12d?- Some otthe'properties-ofthe sheetsxwerefgf v brassy qwe i ateii K0. mseacyelcs lale triawa an ew A end ,w s made r am t .l f iesn f glass-*fiber' cloth (Fiberglasuc fi l'fiyal'ternate qa. rossr ise pply ng inarts by mi htier he fn ep ne res n 9mins;mix ure for. fiinartsiofthe cloth. The coated cloth was thencl'ired for 0.5 hour at 150 F. under 20 p. s. i. pressure,

accepts followed by 0.5 hour at 300 slanderous; ii" pressure. The resulting laminate, whichwas about 0.15 inch thick, had atensile strength of 41,000 to46,000 p. s. i. anda bending modulus of 2,500,000 p. s. i. It's impact strength could notj be measured by conventional-methods,but the laminate easily stopped a 0.45 calibre bullet fired from a distance of feet.

The-Buna S of the-laminating composition may be replaced by the GR-S butadiene-styrene copolymer. s

An electrical casting resin composition was prepared iromstyrene, an unsaturated alkyd resin, polyisobutylene (molecular weight 12,000), the chlorinated diphenyl' resin Arochlor 5460, a crude: divinyl benzene containing 40 per cent by weight of the latter, the balance being ethyl styrene, and p-tert.-butyl catechol as a storag inhibitor." The proportions were:

- I Parts by Ingredient v Weight Sty! 47.2 Unsaturated Alkyd Rosin. 0.8 Polyisobutylcne 23 Aroculor 5460 Q. ii i 23 Divinyi Benzene (crude). a I *6 p-tert.-bulyl-catcchol 0.005

Immediately before use, 1 per cent of lauroyl peroxide was added as a catalyst. The mixture is a syrup whichis easily cast." It will set to a stiff gel in 2 hours at C. and to a wax-like solid in 18 to 24 hours at the same temperature, Some of the properties of the solid resin are:

Tensile strength; 1000 p. s. 1. f Impact strength-izod unnot hed 2.0,inch-pounds Hardness Rockwell 104--15X-60 Heat distortion 84 C.

Temperature at which resin flows under its own weight Above 200 C. Power factor at V 1.0 megacycle" 0.13 per cent Dielectric constant 2.56

The low tensile strength is desirable since it permits ready removal of the cast resin from electrical equipment in case of trouble. I

i Example .6

other electrical casting j resin was prepared as follows:

composition Parts by Ingredient W i t St r, U aturated Alkyd Resin 1. 2 Buns S Rubber (soluble) 5 Arochlor 5460.. 26 Divinyl Benzene (crude). ,.l c. 5

Attention is. directed to. ouridiyisional appli- 1 cationserial nogmisssgniee October i7, eic

wherein there claimed the resin remission; T positionsfor making-electric insulation disclosed but not claimed herein. x

What is clan-nears: Y

I. A resin-form ingcomposition 'useful in laminating processes and consisting 'essentially of monomeric styrene, from 1 to 5yper-cent"by weight thereof of an unsaturated alkyd resin which contains the functional groupingp a eeih pp issi r. hain. a d w i has a molecular weight of'at least .1000, from 2 to -15; per cent by weight: of a ,butadiene-jstyrene copolymeric elastomer, and firom 2 to j per cent;

of diyinylbenzene. .2. A -resin -iormi ng laminating processes andconsisting essentially of a monomeric polymerizable nuclear -monovi nyl aromatic compound, from 0.5 to per cent byweight' -there'of of an.unsaturated alkyd resin.

from the class consisting of divinyl benzene, dia1-. lyl phthalate, allyl acrylate, diallyl etherg'and' glycol diacrylate.

resin-forming weight thereof of a polymerization catalyst consisting of an unsaturated; alkyd resin which, contains the functional grouping 2 to 15 per cent by weightpf "anlastoinei 4. A synthetic resin -consisting essentiallyor" the product of polymerization of the composition of claim 1. ,1

, 5.'Aisynthetic resin consisting essentially of the product of polymerization of the composition of clause.

6. A synthetic resin consisting essentially of the product of polymerization of of claim 3. LOUIS C. RUBENS.

RAYMOND F. BOYER.

REFERENCES CITED file of this patent:

s UNITED STATES-PATENTS mb "Date I.' j

.. v 1,613,673 'Ostromislensky .Jan;'1 1,.192v 2,202,846 Garvey e't a1. ;;1une"4, 1940', 2,356,965 Allison Aug. 2911944" 2,443,735 Kropa June 22, 1948 s FOREIQN'PATENTiff I C untry Datefi f G ea B ita composition ,usefulj inf laminating 'fprocesses consisting,fesseifitially of 'a monomeric polyrm-;-'ri2aole "nuclear ino ovin'yl" aromatic compound, from 0.5 to lO'per cent by" repeated ianm the o yester at: n and? .rmmi

the composition The following references are of record in the: 

3. A RESIN-FORMING COMPOSITION USEFUL IN LAMINATING PROCESSES CONSISTING ESSENTIALLY OF A MONOMERIC POLYMERIZABLE NUCLEAR MONOVINYL AROMATIC COMPOUND, FROM 0.5 TO 10 PER CENT BY WEIGHT THEREOF OF A POLYMERIZATION CATALYST CONSISTING OF AN UNSATURATED ALKYD RESIN WHICH CONTAINS THE FUNCTIONAL GROUPING 